Critical Point for Bose–Einstein Condensation of Excitons in Graphite
Critical point for Bose–Einstein condensation of excitons in graphite Jinhua Wanga,b , Pan Niea,b , Xiaokang Lia,b, Huakun Zuoa,b, Benoˆıt Fauque´ c, Zengwei Zhua,b,1 , and Kamran Behniad aWuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China; bSchool of Physics, Huazhong University of Science and Technology, Wuhan 430074, China; cJeunes Equipes´ de l’Institut de Physique, Unite´ Mixte de Service et de Recherche 3573, CNRS, College` de France, Paris Sciences et Lettres Research University, 75231 Paris Cedex 05, France; and dLaboratoire de Physique et d’Etude´ des Materiaux,´ CNRS, Ecole´ Superieure´ de Physique et de Chimie Industrielles Paris, Paris Sciences et Lettres Research University, 75005 Paris, France Edited by Zachary Fisk, University of California, Irvine, CA, and approved October 15, 2020 (received for review June 22, 2020) An exciton is an electron–hole pair bound by attractive Coulomb nature of EI unexpected in the alternative Peierls-driven charge interaction. Short-lived excitons have been detected by a vari- density wave (CDW) (9). Other indirect signatures of BEC ety of experimental probes in numerous contexts. An excitonic transition have been reported in two-dimensional systems, such insulator, a collective state of such excitons, has been more elu- as quantum wells (11), graphene (12–14), and transition metal sive. Here, thanks to Nernst measurements in pulsed magnetic dichalcogenides heterostructures (15, 16). fields, we show that in graphite there is a critical temperature Here, we present the case of graphite subject to strong mag- (T = 9.2 K) and a critical magnetic field (B = 47 T) for Bose–Einstein netic field where the existence of a thermodynamic phase transi- condensation of excitons.
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